It is commonly known that moulds for making large articles such as wind turbine blades and consisting of two mould parts are closed about a longitudinal hinge line, where the hinges are passive, ie a crane is used to lift one of the mould parts about the hinge line for closure and opening of the mould. When making wind turbine blades, the mould is closed so as to glue two blade shell halves together, said shell halves being produced in separate mould parts.
Danish patent application No DK 2000 01281 discloses an assembly, a drive unit built into the hinge structure lifting and turning a mould part from a position, in which its opening faces upwards, to a position above the other mould part, in which the openings of the two mould parts face each other. The closure mechanism includes an additional means bringing the two mould parts together by means of a parallel linkage mechanism and almost rectilinear movement. This curve linear or almost rectilinear closing movement is necessary when making wind turbine blades, a complete closure at rotation being geometrically impossible unless the hinge axis is arranged at a disadvantageously large distance from the mould cavity.
However, this known solution is encumbered by certain shortcomings with a view to obtaining an accurate and precise positioning of the mould parts and thus of the blade shells one above the other. The reason why is basically the size of the mould assembly and consequently its bulkiness. In order to obtain an accurate positioning of the upper mould part, the closure mechanism according to the above patent application has to be made with such large dimensions so as to avoid slack and elastic deflections that its mere physical size makes it impractical. It is also desirable to perform various manoeuvres with the upper mould part during the closing or the opening of the mould assembly, said manoeuvres not being possible by means of the known solution.